The survival and well being of an organism depend crucially on the ability of its cells to coordinate their gene activities in response to a vast number of cellular and environmental signals. This is often accomplished combinatorially through a large number of protein-protein and protein-DNA interactions. A major goal of post-genome biology is to characterize these interactions and decipher the complex regulatory circuits/networks that they define. Instead of directly dissecting the regulatory program of a specific organism, we investigate different molecular strategies an organism could adopt to integrate and regulate signals. The focus of the proposed research is on combinatorial transcription regulation. We propose experiments to implement a number of novel transcriptional regulatory functions involving two well-characterized E. coli transcription factors. The regulatory functions will be demonstrated in vivo, by quantifying the expression of a reporter gene for different combinations of inducer concentrations. The proposed research is a pilot study aimed at the larger goal of implementing cis-regulatory control involving arbitrary regulatory proteins in a cell. Applying this capability to bacteria endowed with special sensors/receptors, one would be able to design cis-regulatory sequences to recognize and report unique patterns of detectable traits corresponding to specific chemical pollutants or harmful biological agents. Furthermore, the directed evolution approach can in principle be extended to breeding desired promoter sequences in eukaryotic cells. Such approaches could lead to sensitive, non-invasive cellular reporters of complex transcriptional patterns in vivo. The information obtained could be of significant value to the diagnosis and treatment of complex diseases.